“The oldest known spring deposits in the Dixie Valley region are those currently associated with the Dead Travertine (Cottonwood Travertine) springs about 2 km upstream of the mouth of Cottonwood Canyon” (see Appendix 5, of Blackwell et al., 2006). “The deposit drapes the northeast side of the canyon wall over an elevation range of 275 m and is roughly 400 m wide at the base (along the dirt road), 150 m wide at the crown, and 550 m long horizontally. The deposit is fault controlled because Jurassic quartzite is faulted down to the northwest against Jurassic gabbro in a narrow, northeast trending window within the travertine (F. Goff and C.J. Janik, unpublished mapping, 1999). This fault extends beyond the deposit to the northeast up the canyon wall. Rocks within the window and just above the crown of the deposit are highly fractured and contain numerous calcite veins. A sample of dense, honey-colored calcite from one of these veins yielded U/Th disequilibrium and protactinium-231 ages of 182 ± 4 ka and 161 ± 15 ka, respectively (Goff et al., 2002). More recently, Dixon et al. (2003) reported a preliminary U/Th isochron age of 100 ka from four layered travertine samples obtained throughout the deposit. Determination of whether or not these deposits were formed from spring waters of compositions and temperatures different from the cold seeps of today would require considerable additional work. However, it appears that carbonate-rich fluids have discharged in this area for 150 ka or more.”